Means for regulating the speed of direct-current motors.



H. OSBORNE.

MEANS FOR REGULATING THE SPEED OF DIRECT CURRENT MOTORS. APPLIOATIONFILED NOV. 8, 1912.

1,060,208. Q Patented A r. 29, 1913.

3 UNITED STATES PATENT. oF IoE;

HEINRICH OSBORNE, OF GHARLOTTENBURG', GERMANY, ASSIGNOB IO SIEMENS-SCHUGKERT WERKE, M. B. H., OF BERLIN, GERMANY, A CORPORATION OF GERMANY.I

MEANS, FOR BEGULATING THE SPEED OF DIRECT-CURRENT MOTORS.

Specification of LettetaPatent. Application mm November 8, 1912. Serialat. 730,207.

Patented Apr. 29, 1913.

To all whom it may concern:

Be it known that I, HEINRICH OSBORNE, a citizen of the AustroHungarianEmpire, and residing at 'Charlottenburg, near Berlin, Germany, haveinvented certain new and useful Improvements in Means for Regulat- .ingthe Speed of Direct-Current Motors, of

- Leonard system wherein a direct current motor having a constant fieldis supplied atvarying voltages from a special regulating generator, theabove-named condition is only approximately obtained, because the lossof potential due to ohmic resistance in all the leads and the remanenceof the mag;

netic fields, especially at low speeds of the motor, cause the speedsobtained to vary considerably, from their predetermined values.

A primary object of my invention is to obviate this defect, and to thisend I provide means whereby it is possible to obtain speeds of the motorwhich have values which do not appreciably vary from predeterminedvalues de endmg upon the position of the arm of the regulating switch.With the same object in view, a number of methods are already knownwherein these variations from the predetermined values of the speedshave been more or less reduced by employing a special auxiliary dynamo.Accor ing to my nvention, I employ auxiliary machines which cooperateboth with the auxiliary regulating dynamo'tand the main motor, and thesaid variations are thus entirely'dispensed with. I

One illustrative embodiment of my invention is diagrammaticallyrepresentedby way of example in the accompanying drawing.

Theregulating generator 9 is employed to supply current at'varyingvoltages to the motor m, as in the known Ward-Leonard system. Theexciting winding w of the stant an excitation as possible, and theauxcurrent energizing the winding 'w of regulating dynamo} whichtherefore gensaid generator is however energized by two auxiliarymachines 12. it, connected in series, but arranged to generate voltagescounter to each other. The circuit vso formed will be called theauxiliary machine circuit. The auxiliary machine h, is driven b I mannert at it has a speed proportional to that of the motor. The otherauxiliary machine hi'can be coupled mechanically with the regulatinggenerator. It is however preferable that-the machine h, beycoupled witha special constant-speed motor inorder that itv may be independent ofchanges in speed of the generator g, for this speed in some cases, 6. g.inv the known Il'gner system, may vary within certain limits.

Both the motor m and the auxiliary machine h, are separately excited.with'as coniliary machine it, receives an excitation dependent upon theadjustment pf the regulating switch 8. The regulating generator 9 canhave not only an exciting winding in the auxiliary machine circuit asalready stated, but also an additional exciting winding which may beeither a self-exciting winding e or a winding supplied from a separatesource. The auxiliary machine it, is preferably provided with a compoundwinding-c.

My improved system of regulation operates in the following manner :-Assoon as the separately excited winding of machine 72., receives current,the latter generatesha t e erates a voltage. The motor m and conseuentlythe auxiliary machine It, will therefore begin to rotate. The lower thespeed of the motor, the greater will be the difference of voltagebetween the two auxiliary machines and consequently the greater theexcitation of the regulating dynamo. The

motor m thus always tends to acquire a speed determined by the positionof the regulating switch 8'. With an increase in the motor speed thecurrent in 1 the auxiliary circuit falls until the motor'speed hasattained the value which corresponds to that field strength given by thewinding 1 which is just requisite to produce the correct voltage in thegenerator g. Should the speed of the meter vary for any reason such asowing to change of load and so on, there is a simultaneous change in thevoltage of the auxiliary machine h,, and this causes a considerableincrease or diminution in the cur- .rent in the exciting winding of thegenerator, the effect lasting until the motor has again come to itsproper speed. To compensate for the efiect of ohmic resistance in theauxiliary machine circuit, and so avoid a certain difference of voltagein the auxiliary. machine circuit which would depend solely upon thecurrent in this circuit, and to thus avoid the speed of the motor beingchanged in the same degree, the auxiliary. machine k is preferablycompounded, as is shown in the drawing. Any desired strength of currentcould then beemployed in the auxiliary machine circuit, such currentbeing independent of the adjustment of the regulator-s. The particularcurrent values employed are however; always so influenced by the changeof; voltage of the auxiliary machine'h, that .3. value results whichisjust sufiicient to excite the d namo to give the exact desired motorspee 'jAs the strength of current'in the auxiliary circuit is thusneither "dependent on the speed nor on'the' separate excitation of theauxiliary ma-- chine 71. it is possible to reduce'it to such an extentthat, the regulating dynamo re- .ceives an additional excitation eitherfrom a separate source, or from a self-exciting winding 0. The currentin the winding w is then only that required to supply the difi'erencebetween the excitation needed to give the'correct speed to the motor andthe excitation due to the coil e. By adopting this arrangement muchsmaller auxiliary machines can be employed.

1. In means for regulating the speed of a direct-current motor, thecombination with a separately excited motor anda generator energizingsaid motor and having a field winding, of two auxiliary dynamos, thefirst having a regulatable field, and the second being separatelyexcited and mechanically connected to said motor; the said auxiliarydynamos being connected counter to one another, and thus energizing saidfield winding.

2. In means for regulating the speed of a direct-current motor, thecombination with energizing said motor and having a field winding, oftwo auxiliary dynamos, the first having a regulatable field, and thesecond'being separately excited and mechanically connected to saidmotor, the said auxiliary dynamos being connected counter to oneanother, and being in series witha portion of said field winding, theremainder of said field winding being a self-exciting winding.

4. In means for regulating the speed of a direct-current motor, thecombination with a separately excited motor and a generator energizingsaid motor and having a field winding, of two auxiliary dynamos, thefirst being compounded and having a regulatable field, and the secondbeing separately excited and mechanically connected to said motor, thesaid auxiliary dynamos being connected counter to one another, and thusenergizing said field winding.

5. In means for regulating the speed of a direct-current motor, thecombination with a separately excited motor and a generator energizingsaid motor and having a field Wind ng, of two auxiliary dynamos, the

first having a regulatable field and being driven at constant speed andthe second being separately excited and mechanically connected to said Imotor, the said auxiliary dynamos being connected counter to one an- 4other, and thus energizing said field Wind- 1ng. y t

In" testimony whereof, I havesigned my name to this specification in thepresence of a two witnesses.

v HEINRICH OSBORNE. Witnesses:

WOLDEMAR HAUPT,

HENRY HASPER.

